25. February 2026

In 1933, the contract for the North–South railway was signed with the Danish engineering company Kampsax. The project began with its most formidable challenge: the Northern Alborz Mountains, rising sharply toward the Caspian coast. Several European companies had already failed to force a railway through the Alborz range. The greatest obstacle lay in the steep incline leading to the Gaduk Tunnel and the vast valley carved between two mountains. It seemed almost impossible terrain for a train.